As databases are used by a greater variety of people, highly technical methods of designing them are giving way to more human, user-centered approaches. The article describes a human approach to designing a complex, multiuse database with limited resources. The article introduces a simple data modeling tool, the entity-relationship (E-R) diagram, that crosses professional boundaries and enables providers, researchers, and programmers to communicate more easily. Constructing an E-R diagram provides a human description of the social health maintenance organization (S/HMO) multisite demonstration project. This project, now in its tenth year, provides integrated acute and community-based in-home services to allow frail elderly HMO members to stay in their homes. After briefly reviewing the three types of databases and three rules of thumb for designing a relational database, the article shows how a simple E-R diagram can clarify the management and research issues of the S/HMO health care model. The article concludes with a brief discussion of the benefits and limits of housing research-related health data in a relational database.